22 research outputs found

    An Updated Search of Steady TeV γ−\gamma-Ray Point Sources in Northern Hemisphere Using the Tibet Air Shower Array

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    Using the data taken from Tibet II High Density (HD) Array (1997 February-1999 September) and Tibet-III array (1999 November-2005 November), our previous northern sky survey for TeV γ−\gamma-ray point sources has now been updated by a factor of 2.8 improved statistics. From 0.0∘0.0^{\circ} to 60.0∘60.0^{\circ} in declination (Dec) range, no new TeV γ−\gamma-ray point sources with sufficiently high significance were identified while the well-known Crab Nebula and Mrk421 remain to be the brightest TeV γ−\gamma-ray sources within the field of view of the Tibet air shower array. Based on the currently available data and at the 90% confidence level (C.L.), the flux upper limits for different power law index assumption are re-derived, which are approximately improved by 1.7 times as compared with our previous reported limits.Comment: This paper has been accepted by hepn

    VIKOR Method for Interval Neutrosophic Multiple Attribute Group Decision-Making

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    In this paper, we will extend the VIKOR (VIsekriterijumska optimizacija i KOmpromisno Resenje) method to multiple attribute group decision-making (MAGDM) with interval neutrosophic numbers (INNs). Firstly, the basic concepts of INNs are briefly presented. The method first aggregates all individual decision-makers’ assessment information based on an interval neutrosophic weighted averaging (INWA) operator, and then employs the extended classical VIKOR method to solve MAGDM problems with INNs. The validity and stability of this method are verified by example analysis and sensitivity analysis, and its superiority is illustrated by a comparison with the existing methods

    STUDY ON CREEP PERFORMANCE OF LAUNCH CANISTER UNDER LONG-TERM STORAGE

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    In this paper, the creep performance of multi-barrel rocket launch canister under long-term stacking storage is studied. Based on the Bailey-Norton model, the creep model of the frame material of a launch canister was established. Constant stress tensile creep test at different stress levels under room temperature was carried out on the frame materials of the launch canister and the creep model parameters were obtained by test data fitting. The three-dimensional finite element model of the launch canister was established in the ABAQUS software environment and the creep deformation of the launch canister after long-term stacking storage was studied. The results indicated that the bottom layer of the launch canister frame presented an extended residual deformation when the stacking storage solution with original support pad was used. Therefore a position adjustment program of the support pad was put forward and the residual deformation of the launch canister frame after long-term storage could be significantly reduced, thus the performance requirements for the launch canister are guaranteed.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

    Creep prediction of GFRP directors in a multiple launch rocket system under long-term stacking storage

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    During long-term stacking storage, creep deformation of polymeric composite directors used in multiple launch rocket systems can appear, which affects rocket launch. In this work, E-glass/epoxy 6509 composite laminates were prepared and 60/60 min creep/creep-recovery tests were carried out in the transverse and shear directions at different stress levels. Parameters of the Schapery’s nonlinear viscoelastic equation were obtained based on the test data. Then, a three-dimensional nonlinear viscoelastic constitutive model based on Schapery’s equation was implemented in the standard finite element code UMAT and a finite element model was developed to predict the creep deformation of the composite directors after 15 years of stacking storage. The effect of creep deformation on rocket launching was also studied. The results show that the residual deformation of the directors is a saddle-shaped distribution in three-dimensional space, the maximum residual deformation is 0.24 mm, and the minimum residual deformation is 0.22 mm. The creep deformation of the director causes a significant increase in the contact-collision force during launching, resulting in a decrease in the rocket run-off track velocity.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

    Study on the early detection of gastric cancer based on discrete wavelet transformation feature extraction of FT-IR spectra combined with probability neural network

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    Abstract. This paper introduces a new method for the early detection of gastric cancer using a combination of feature extraction based on discrete wavelet transformation (DWT) for horizontal attenuated total reflectance-Fourier transform infrared spectroscopy (HATR-FT-IR) and classification using probability neural network (PNN). 344 FT-IR spectra were collected from 172 pairs of fresh normal and abnormal stomach tissue's samples. After preprocessing, 5 features were extracted with DWT analysis. Based on the PNN classification, all FT-IR spectra were classified into three categories. The accuracy of identifying normal gastric tissue, early gastric cancer tissue and gastric cancer tissue samples were 100.00, 97.56 and 100.00%, respectively. This result indicated that FT-IR with DWT and PNN could effectively and easily diagnose gastric cancer in its early stages

    Experimental demonstration of phase-matching and Sagnac effect in a millimeter-scale wedged resonator gyroscope

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    The highly efficient coupling of light from conventional optical components to optical mode volumes lies in the heart of chip-based micro-devices, which is determined by the phase-matching between propagation constants of fiber taper and the whispering-gallery-mode (WGM) of the resonator. Optical gyroscopes, typically realized as fiber-optic gyroscopes and ring-laser gyroscopes, have been the mainstay in diverse applications such as positioning and inertial sensing. Here, the phase-matching is theoretically analyzed and experimentally verified. We observe Sagnac effect in a millimeter-scale wedged resonator gyroscope which has attracted considerable attention and been rapidly promoted in recent years. We demonstrate a bidirectional pump and probe scheme, which directly measures the frequency beat caused by the Sagnac effect. We establish the linear response between the detected beat frequency and the rotation velocity. The clockwise and counterclockwise rotation can also be distinguished according to the value of the frequency beat. The experimental results verify the feasibility of developing gyroscope in WGM resonator system and pave the way for future development.Comment: 7 pages, 6 figure

    Conservation Significance of the Rare and Endangered Tree Species, Trigonobalanus doichangensis (Fagaceae)

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    Trigonobalanus doichangensis is a rare and endangered species with important evolutionary value and extremely small populations. We investigated the genetic diversity of T. doichangensis to provide information on its effective preservation. We used genotyping-by-sequencing (GBS) technology to assess the genetic diversity, genetic structure and gene flow of the six populations of T. doichangensis. Analysis of SNPs indicated that there was high genetic diversity in the ML and XSBN populations of T. doichangensis. FST values showed moderate genetic differentiation among the populations of T. doichangensis. Meanwhile, admixture, principal components and gene flow analyses indicated that the populations of T. doichangensis are not genetically separated in accordance with their geographical distributions. Habitat destruction and excessive exploitation may have led to a low gene flow, which has in turn resulted in the differences in seed and seedling morphological traits among populations. Based on these findings, we recommend that T. doichangensis be conserved through in situ approaches and artificial seedlings, including preservation of each extant population. Particularly, the ML and XSBN populations have high diversity and more ancestral information, so these two populations should be considered as conservation priorities, and seeds should be collected to obtain germplasm and increase the genetic diversity

    Isolation, Purification, and Structural Characterization of Polysaccharides from <i>Codonopsis pilosula</i> and Their Anti-Tumor Bioactivity by Immunomodulation

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    The activity of polysaccharides is usually related to molecular weight. The molecular weight of polysaccharides is critical to their immunological effect in cancer therapy. Herein, the Codonopsis polysaccharides of different molecular weights were isolated using ultrafiltration membranes of 60- and 100-wDa molecular weight cut-off to determine the relationship between molecular weight and antitumor activities. First, three water-soluble polysaccharides CPPS-I (100 wDa) from Codonopsis were isolated and purified using a combination of macroporous adsorption resin chromatography and ultrafiltration. Their structural characteristics were determined through chemical derivatization, GPC, HPLC, FT–IR, and NMR techniques. In vitro experiments indicated that all Codonopsis polysaccharides exhibited significant antitumor activities, with the tumor inhibition rate in the following order: CPPS-II > CPPS-I > CPPS-III. The treatment of CPPS-II exhibited the highest inhibition rate at a high concentration among all groups, which was almost as efficient as that of the DOX·HCL (10 μg/mL) group at 125 μg/mL concentration. Notably, CPPS-II demonstrated the ability to enhance NO secretion and the antitumor ability of macrophages relative to the other two groups of polysaccharides. Finally, in vivo experiments revealed that CPPS-II increased the M1/M2 ratio in immune system regulation and that the tumor inhibition effect of CPPS-II + DOX was superior to that of DOX monotherapy, implying that CPPS-II + DOX played a synergistic role in regulating the immune system function and the direct tumor-killing ability of DOX. Therefore, CPPS-II is expected to be applied as an effective cancer treatment or adjuvant therapy
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